If 100% accurate this is even more amazing than before! Wow! Great job NVIDIA. I am excited just thinking about the mid and high end maxwell gpu’s.

Hi, hk_14

We has the same measured, around ~75W per card for Gigabyte 750 Ti.

BTW: We only can get 290 KH for the 6 card rig(TDP 65.5), also not stable(not sure is this caused by CudaMiner).

The measurement above is only for the card, the watt meter is placed between the power supply and the powered extended measuring all the power that goes to the video card. This is the exact power consumed only by the video card with stock and with overclocked settings. When measuring the full system power draw with with card at idle state and when you start mining you cannot get adequate result only for the video card’s power consumption, because not only the card has increased power consumption, but the whole system has increased load – CPU, memory, motherboard etc. use more power as compared to when the system is in idle (power saving mode). Our goal was to measure the exact power usage of the GTC 750 Ti only, also if you are interested the idle power consumption of the card only is about 2-4W.

Haigent,

Not sure what kind of cards you are running but I have 5 EVGA FTWs running at 305-315khs each, very stable as well. Try the T5X24 kernel setting or T10X24.

I have an EVGA version of this card. I have the GPU clock speed at +135 and the memory at +670 but can’t get over 301khs. I get the highest hash rate with T20x20. I’ve tried increasing the voltage but I can’t seem to get the memory clock rate much higher; and can’t get the hash rate higher at all. Is there anything I can do to squeeze anything else out of this?

@admin :
You used a powered PCIe riser, which is powered via a molex connector, right ?
And from what I understand, you measured the draw from that molex connector ?

If so, you are neglecting the power sent from the motherboard PCIe to the graphic card via the flat ribbon cable. That could explain your very optimistic result.

You could try to measure the wall power outlet draw from 6 such cards, you’ll get way less interesting results. Sadly :(

nVidia would be the best competitor to Scrypt Asic if they could reach such a high KH/s per watt !

Are you sure that the USB 3.0 cable doesn’t drive a bit of power ? By design, it can bring 100 Watts, so the cable is no limiter to what to motherboard can send through its PCI Express ports.
A motherboard can deliver power through PCIe even without additionnal molex.

A way to concur your findings would be to measure the total power draw from a 6 x 750 Ti Scrypt rig. Hope you are right!

Thanks for the detailed information. As I said, I hope you are right, and you seems very confident that you are.
I just don’t understand why every other person measuring their power draw with Kill-A-Watt and similar instrument find around 60W, and not 30-37W as you do.

May it be possible that the reference card is more power-efficient than custom OEM design with additionnal PCIe 6 pin connector?

Kill-A-Watt measures the power at the power outlet of the whole system and measuring the system at idle and then with the video card mining and subtracting the numbers does not give you accurate results for the card consumption only (it also takes into account the efficiency of the PSU). When you start mining with the card it also increases the overall power consumption of the whole system (processor, motherboard, memory…), that is why you are getting around 60W and not more like 40W for example. Do have in mind that the Power Target limiter of these cards is set to 38.5W and that goes not only for the reference board, so the built-in power limiting functionality of the card will not allow it to go past this power consumption anyway… unless you modify the BIOS to increase the limit.

decagrog, in fact you are only partially right. The card does use 3.3V and by PCI-E specs this can go up to 3A. However this 3.3V line is not going through the USB cable at all, as we’ve said the USB 3.0 cable is used only for the data lanes. All of the power to the video card goes through the 12V line provided by the 4-pin molex power connector that is plugged in the PCI-E USB Extender…

The board of the extender where you place the video card has a single AZ1084 voltage regulator that does take 12V input and outputs 3.3V in order to supply the video card with the required 3.3V along with the 12V power. There are no like extra up to 10W on top of what we have measured because of the 3.3V line, the power consumption of this line is included in what we have measured on the 12V input line.

decagrog, we are gong to be doing some more tests with different cards as well, including ones with external PCI-E power connector soon. It seems that pretty much all PCI-E Extenders that use USB 3.0 cables follow this design with a 3.3V power regulator onboard, we have picked up ours from eBay. Just search for “PCI-E USB 3.0 Extender” or “PCI-E USB 3.0 Riser”

I just bought a 750 Ti after reading this, and I would greatly appreciate you run more tests, I’m also in the group of “there’s no way”….

Where did u get the watt meter from? What’s the name of it. I have been searching for one for couple weeks now.

I have read that the use of the USB risers can have a negative effect on hash rates due to the fact that there are not enough lanes of data and that the asrock risers that use sata cables to transfer the data work better. Have you thought about doing any testing in this matter?

same motherboard, Corsair 750W Gold PSU, using cudaminer, however why is my power draw in the 600s? With my original Ultra power supply, I was drawing close to 700W.

What kernel are you guys using?

G3220 overclocked and unvolted to 800Mhz, 0.6V
1333mhz undervolted to 1.5V